Manufacture of polyvinyl alcohol threads



Patented May 7, 1946 2,899,970 MANUFACTURE OF POLYVINYL ALCOHOL THREADS Donald Leonard Wilson, Ooventry, England, as-

algnor to Courtanids,

limited, tendon, Enlland, a British company No Drawing. Application June 20, 1941, Serial No. 309,038. In Great Britain August 2, 1940 (01. ii-s4) 3Claims.

This invention relates to the manufacture and production from polyvimrl alcohol of artificial filaments, threads and the like, hereinafter referred to as threads.

According to the present invention an aqueous solution of water-soluble polyvinyl alcohol is extruded into a bath consisting of from 96 to 88 per cent of an organic liquid having an appreciable solvent powerior water or a mixture of such liquids together with water.

Generally speaking a lower temperature and a higher concentration of the polyvinyl alcohol solutions tend to cause an increase in the viscosity, and the concentration and temperature of the solution should be adopted so that a spinning solution is obtained of suitable viscosity for ex trusion. Such viscosity may conveniently n 3 poises at 25 centigrade, but if the conditions of extrusion difler from those described in the accompanying examples a solution of correspondingly diflerent viscosity should be employed. Polyvinyl alcohol solutions of sufiicierit concentration when kept below certain temperatures increase in viscosity and finally take the form of gels. I generally prefer to use a solution of polyvinyl alcohol such concentration in relation to the temperature employed that no change in viscosity occurs on standing.

The organic liquid used according to this invention must be one which is capable of removing the water from the aqueous solution of polyvinyl alcohol and thereby causing the polyvinyl alcohol to form a thread. Examples of liquids which may be used are acetone, ethyl lactate and ethylene glycol mono-ethyl ether, known indus= trially as Cellosolve." The thread on emerging from the bath may be dried and wound on to a suitable device.

The bath into which extrusion takes place will consist of from 98 to 88 per cent at one or more organic liquids mixed with water. While the threads produced are in course 01 being dried the composition of the liquid remaining on the threads is liable to change. When this leads to an increase in the proportion of water in the liquid there is a strong tendency for the filaments to stick together, and ii an attempt is made to obviate this by reducing the concentration oi water in the spinning bath, there is a risk of reaching a condition in which the threads are precipitated in a form of low tensile strength, characterised by having a marked dullness and opacity. In such cases it is necessary to pass the threads through a second bath of difierent composition from that 01' the first before drying them. The second bath may contain a liquid or mixture of liquids capable of dissolving the solvent used in the first bath, and may include a proportion of water and/or other substances. It may, for instance, consist of a solution of hydroxy-ethoxy-ethy1 ether and water, or of ethylene chlorhydrin and water.

If desired the threads may be stretched in order to improve their properties, for instance to increase their tensile strength, in which case it is oi'ten convenient to carry. out any stretching which may be required while the thread is passing through this second bath.

The polyvinyl alcohol threads produced according to this invention are considerably weekened by cold water and dissolved by hot water. For many uses it is desirable to impart to the threads at suitable degree of resistance to the action of water. This can be carried out in several ways, tor example, by treatment with formaldehyde or by a treatment with an acid chloride as described in my co-pending application No. scenes, filed June 20, 1941.

The following examples illustrate methods or carrying out the present invention although the invention is not restricted to these examples.

Example 1 Polyvinyl alcohol is dissolved in water by warming to 60 centigrade to give a solution of 14 per cent concentration, which is cooled, filtered, and decorated. This solution, which has a viscosity of 3 poises at 25 centigrade, is extruded through a Jet containing 200 holes, each 0.003 inch in dismeter. into a bath consisting of 04 per cent acetone and 6 per cent water kept at a temperature of from 28 to 30 centigrade. The thread so produced is passed, on emerging irom the bath, over a roller running at a peripheral velocity or 6.8 metres per minute, then through a bathconsisting of per cent hydroxy-ethoxy ethyl ether The thread is afterwards dried on the spool at 60 centigrade. It has a denier of 124, a. dry tenacity of 2.52 grams per denier, and dry extensibility of 12.4 per cent.

Example 2 A solution oi polyvinyl alcohol similar to that used in Example 1 is extruded through a jet containing 200 holes, each 0.003 inch in diameter,

intoabatheonslstingoi'ildpercentacetoneand 6 per cent water, kept at a temperature oi rrom 2a to 30 centigrade. The thread so produced is passed, after travelling for 100 centimetres through the bath, over a roller running at a pcripheral velocity or 6.8 metres per minute, then for 80 centimetres through a bath consisting oi 80 per cent ethylene chlorhydrin and 20 per cent water, kept at a temperature of from 29 to 31 centlgrade. It is wound up on a spool at a rate or 31 metres per minute. thus being stretched to 4.5 times its former length. The thread is afterwards dried on the spool at 46 centigrade. It is lustrous and has a denier of 68. a dry tenacity of 2.03 grams per denier, and dry extensibility oi 15.8 per cent. The filaments have an average denier oi 0.34. i

What I claim is:

1. A process or producing lustrous artificial illaments, threads and the like of polyvinyl alcohol which comprises dissolving polyvinyl alcohol in water to give a non-gelatinous solution having a constant viscosity of about 3 poises at 25 0., extruding the solution through a multi-holeiet into a coagulating bath consisting of 04% of acetone and 6% of water to form a thread, passing the thread through a bath or 50% hydroxy-ethoiw-ethyl ether and 50% of water, stretching the thread while it is passing through the second bath w and thereafter drying the thread.

2. A process of producing lustrous artificial n1- aments, threads and the like of polyvinyl alcohol which comprises dissolving polyvinyl alcohol in water to give a non-gelatinous solution havins a constant viscosity of about 3 poises at C.; extruding the solution through a multi-hole let into a coagulating bath consisting of 04% of acetone and 8% or water to form a thread: the thread through a liquid bath selected from the group of liquids conslsting 01' a mixture or about hydroxy-ethoxy-ethyl ether and about 50% of water, and a mixture 0! about of ethylene chlorhydrin and about 20% 0! water; stretching the thread while it is passing through the second bath; and thereafter drying the thread.

3. A process of producing lustrous artificial mamcnts. threads and the like of polyvinyl alcohol which comprises dissolving polyvinyl alcohol in water to give a non-gelatinous solution havin a constant viscosity 01' about 3 poises at 25 0.; extruding the solution througha multi-hole jet into a coagulating bath consisting of 04% or acetone and 6% 0! water to form a thread; passing the thread through a bath or about 80% ethylene chlorhydrin and about 20% oi water; stretching the thread while it is Passing through the second bath: and thereafter drying the thread.

DONALD LEONARD WILSON.

Certificate oi. Correction Patent No. 2,399,970.

May 7, 1946.

DONALD LEONARD WILSON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, first column line 40, strike out from 9 6 to 88 per cent of; and thatthe said Letters Patent shouid be read with this correction therem that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 9th day of July, A. D. 1946.

[snap] LESLIE FRAZER,

First Assistant Commissioner of Patents.

intoabatheonslstingoi'ildpercentacetoneand 6 per cent water, kept at a temperature oi rrom 2a to 30 centigrade. The thread so produced is passed, after travelling for 100 centimetres through the bath, over a roller running at a pcripheral velocity or 6.8 metres per minute, then for 80 centimetres through a bath consisting oi 80 per cent ethylene chlorhydrin and 20 per cent water, kept at a temperature of from 29 to 31 centlgrade. It is wound up on a spool at a rate or 31 metres per minute. thus being stretched to 4.5 times its former length. The thread is afterwards dried on the spool at 46 centigrade. It is lustrous and has a denier of 68. a dry tenacity of 2.03 grams per denier, and dry extensibility oi 15.8 per cent. The filaments have an average denier oi 0.34. i

What I claim is:

1. A process or producing lustrous artificial illaments, threads and the like of polyvinyl alcohol which comprises dissolving polyvinyl alcohol in water to give a non-gelatinous solution having a constant viscosity of about 3 poises at 25 0., extruding the solution through a multi-holeiet into a coagulating bath consisting of 04% of acetone and 6% of water to form a thread, passing the thread through a bath or 50% hydroxy-ethoiw-ethyl ether and 50% of water, stretching the thread while it is passing through the second bath w and thereafter drying the thread.

2. A process of producing lustrous artificial n1- aments, threads and the like of polyvinyl alcohol which comprises dissolving polyvinyl alcohol in water to give a non-gelatinous solution havins a constant viscosity of about 3 poises at C.; extruding the solution through a multi-hole let into a coagulating bath consisting of 04% of acetone and 8% or water to form a thread: the thread through a liquid bath selected from the group of liquids conslsting 01' a mixture or about hydroxy-ethoxy-ethyl ether and about 50% of water, and a mixture 0! about of ethylene chlorhydrin and about 20% 0! water; stretching the thread while it is passing through the second bath; and thereafter drying the thread.

3. A process of producing lustrous artificial mamcnts. threads and the like of polyvinyl alcohol which comprises dissolving polyvinyl alcohol in water to give a non-gelatinous solution havin a constant viscosity 01' about 3 poises at 25 0.; extruding the solution througha multi-hole jet into a coagulating bath consisting of 04% or acetone and 6% 0! water to form a thread; passing the thread through a bath or about 80% ethylene chlorhydrin and about 20% oi water; stretching the thread while it is Passing through the second bath: and thereafter drying the thread.

DONALD LEONARD WILSON.

Certificate oi. Correction Patent No. 2,399,970.

May 7, 1946.

DONALD LEONARD WILSON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, first column line 40, strike out from 9 6 to 88 per cent of; and thatthe said Letters Patent shouid be read with this correction therem that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 9th day of July, A. D. 1946.

[snap] LESLIE FRAZER,

First Assistant Commissioner of Patents. 

